Gilead to Present Wide-Ranging New Data on Treatment and Diagnosis of Liver Diseases at The Liver Meeting® 2018

Gilead Sciences, Inc. (Nasdaq: GILD) today announced that data from the
company’s liver disease research and development programs in
nonalcoholic steatohepatitis (NASH), primary sclerosing cholangitis
(PSC), hepatitis B virus (HBV) infection and hepatitis C virus (HCV)
infection will be presented at The Liver Meeting® 2018 in San
Francisco from November 9-13, 2018. The data reflect Gilead’s ongoing
commitment to advancing the care of patients with serious liver diseases.

“Gilead has transformed the treatment of viral liver diseases with
innovative medicines that have cured HCV and significantly improved
treatment of HBV for millions around the world,” said John McHutchison,
AO, MD, Chief Scientific Officer, Head of Research & Development, Gilead
Sciences. “Today, we are working to bring this expertise and commitment
to other serious liver diseases with significant unmet medical needs,
such as advanced fibrosis due to NASH and PSC – two diseases with no or
limited treatment options.”

Advanced Fibrosis due to NASH

Individuals with advanced fibrosis, defined as bridging fibrosis (F3) or
cirrhosis (F4), are at a significantly higher risk of liver-related
mortality. Gilead is advancing multiple investigational compounds for
the treatment of advanced fibrosis due to NASH. Data being presented at
the meeting further elucidate the potential role and safety profile of
three compounds in development.

Hepatic metabolomics and plasma microRNA analysis of combinations of
an ASK1 inhibitor, an ACC inhibitor, and an FXR agonist in the rat
choline-deficient high fat diet model reveal reductions in oxidative
stress, inflammation and fibrosis (poster #1265)

Currently, liver biopsy is the standard method to diagnose advanced
fibrosis due to NASH. This invasive and costly procedure presents
challenges to appropriate diagnosis and treatment. Data being presented
at The Liver Meeting describe the potential role and sequence of
noninvasive tests in the diagnosis of advanced fibrosis due to NASH and
patient-reported outcomes from two global Phase 3 trials evaluating the
investigational ASK1 inhibitor selonsertib.

Routinely available noninvasive tests discriminate advanced fibrosis
due to NASH in the Phase 3 STELLAR trials of the ASK1 inhibitor
selonsertib (poster #1674)

Severe impairment of patient-reported outcomes in patients with
advanced fibrosis due to NASH (poster #1683)

Advanced fibrosis based on noninvasive tests in NASH is associated
with impairment of patient-reported outcomes (poster #1991)

PSC

Data will be presented from a Phase 2 trial evaluating the
investigational non-steroidal farnesoid X receptor (FXR) agonist GS-9674
in PSC. PSC is a rare and chronic condition that causes inflammation and
scarring of the bile ducts, which can lead to liver failure. There are
limited treatment options currently available for patients with PSC.

Data will also be presented from Gilead’s ongoing program directed at
achieving a functional cure for HBV by maintaining viral suppression
without ongoing therapy. GS-9688, an investigational oral selective
toll-like receptor 8 (TLR8) agonist, is the subject of several studies
to be presented, including first-in-human clinical results and Phase 1b
results from evaluation in patients with chronic hepatitis B.

GS-9674, selonsertib and GS-9688 are investigational compounds and are
not approved by the U.S. Food and Drug Administration (FDA) or any other
regulatory authority. Their safety and efficacy have not been
established.

Viral Hepatitis Treatment

Viral hepatitis presentations include studies of Epclusa®
(sofosbuvir 400mg/velpatasvir 100mg) and Harvoni® (ledipasvir
90mg/sofosbuvir 400mg) in difficult to cure HCV populations and data
demonstrating the role of Vemlidy® (tenofovir alafenamide
25mg, TAF) in the management of chronic hepatitis B.

EPCLUSA and HARVONI are each indicated in the U.S. for the treatment of
chronic HCV infection in patients with no cirrhosis or compensated
cirrhosis: EPCLUSA for adults with genotypes 1-6; and HARVONI for
patients 12 years and older with genotypes 1, 4, 5 and 6. VEMLIDY is
indicated for the treatment of chronic HBV infection in adults with
compensated liver disease. The US product labels for EPCLUSA, HARVONI,
and VEMLIDY each contain a BOXED WARNING: for EPCLUSA and HARVONI, the
risk of hepatitis B reactivation in HCV/HBV co-infected patients; and
for VEMLIDY, the risk of post-treatment acute exacerbation of HBV. See
below for U.S. Important Safety Information.

The safety and efficacy of EPCLUSA in HCV patients undergoing dialysis
and HARVONI in HCV patients ages 3 to up to 6 years of age have not been
established.

Test all patients for evidence of current or prior hepatitis B virus
(HBV) infection before initiating treatment with HARVONI or EPCLUSA. HBV
reactivation has been reported in HCV/HBV coinfected patients who were
undergoing or had completed treatment with HCV direct acting antivirals
(DAAs) and were not receiving HBV antiviral therapy. Some cases have
resulted in fulminant hepatitis, hepatic failure, and death. Cases have
been reported in patients who are HBsAg positive, in patients with
serologic evidence of resolved HBV, and also in patients receiving
certain immunosuppressant or chemotherapeutic agents; the risk of HBV
reactivation associated with treatment with HCV DAAs may be increased in
patients taking these other agents. Monitor HCV/HBV coinfected patients
for hepatitis flare or HBV reactivation during HCV treatment and
post-treatment follow-up. Initiate appropriate patient management for
HBV infection as clinically indicated.

Contraindications

If HARVONI or EPCLUSA is used in combination with ribavirin (RBV), all
contraindications, warnings and precautions, in particular pregnancy
avoidance, and adverse reactions to RBV also apply. Refer to RBV
prescribing information.

Warnings and Precautions

Serious Symptomatic Bradycardia When Coadministered with Amiodarone:
Amiodarone is not recommended for use with HARVONI or EPCLUSA due to the
risk of symptomatic bradycardia, particularly in patients also taking
beta blockers or with underlying cardiac comorbidities and/or with
advanced liver disease. A fatal cardiac arrest was reported in a patient
taking amiodarone who was coadministered a sofosbuvir containing
regimen. In patients without alternative, viable treatment options,
cardiac monitoring is recommended. Patients should seek immediate
medical evaluation if they develop signs or symptoms of bradycardia.

Risk of Reduced Therapeutic Effect Due to Use with P-gp Inducers
and/or Moderate to Potent Inducers of CYP: Rifampin, St. John’s wort
and carbamazepine are not recommended for use with HARVONI or with
EPCLUSA. P-gp inducers may significantly decrease ledipasvir, sofosbuvir
and/or velpatasvir plasma concentrations. Moderate to potent inducers of
CYP2B6, CYP2C8 or CYP3A4 may significantly decrease sofosbuvir and/or
velpatasvir plasma concentrations.

Adverse Reactions

The most common adverse reactions (≥10%, all grades) with HARVONI were
fatigue, headache, and asthenia.

The most common adverse reactions (≥10%, all grades) with EPCLUSA were
headache and fatigue; and when used with RBV in decompensated cirrhotics
were fatigue, anemia, nausea, headache, insomnia, and diarrhea.

Drug Interactions

HARVONI: Coadministration is not recommended withoxcarbazepine,
phenobarbital, phenytoin, rifabutin, rifapentine, and
tipranavir/ritonavir due to decreased concentrations of ledipasvir and
sofosbuvir; or with co-formulated
elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate due
to increased concentrations of tenofovir; or with simeprevir due to
increased concentrations of ledipasvir and simeprevir; or with
rosuvastatin due to increased concentrations of rosuvastatin.

EPCLUSA: Coadministration is not recommended with topotecan due
to increased concentrations of topotecan; or with proton-pump
inhibitors, oxcarbazepine, phenobarbital, phenytoin, rifabutin,
rifapentine, efavirenz, and tipranavir/ritonavir due to decreased
concentrations of sofosbuvir and/or velpatasvir.

Consult the full Prescribing Information for HARVONI and EPCLUSA for
more information on potentially significant drug interactions, including
clinical comments.

INDICATION for HARVONI

HARVONI is indicated for the treatment of adults with chronic hepatitis
C virus genotype (GT) 1, 4, 5, or 6 infection without cirrhosis or with
compensated cirrhosis. HARVONI is used with ribavirin in GT 1 adults
with decompensated cirrhosis and in GT 1 or 4 adult liver transplant
recipients without cirrhosis or with compensated cirrhosis.

INDICATION for EPCLUSA

EPCLUSA is indicated for the treatment of adults with chronic hepatitis
C virus genotype 1, 2, 3, 4, 5, or 6 infection without cirrhosis or with
compensated cirrhosis and in combination with ribavirin for those with
decompensated cirrhosis.

Discontinuation of anti-hepatitis B therapy, including VEMLIDY, may
result in severe acute exacerbations of hepatitis B. Hepatic function
should be monitored closely with both clinical and laboratory follow-up
for at least several months in patients who discontinue anti-hepatitis B
therapy, including VEMLIDY. If appropriate, resumption of anti-hepatitis
B therapy may be warranted.

Warnings and Precautions

Risk of Development of HIV-1 Resistance in HBV/HIV-1 Coinfected
Patients: Due to this risk, VEMLIDY alone should not be used for the
treatment of HIV-1 infection. Safety and efficacy of VEMLIDY have not
been established in HBV/HIV-1 coinfected patients. HIV antibody testing
should be offered to all HBV-infected patients before initiating therapy
with VEMLIDY, and, if positive, an appropriate antiretroviral
combination regimen that is recommended for HBV/HIV-1 coinfected
patients should be used.

New Onset or Worsening Renal Impairment: Cases of acute renal
failure and Fanconi syndrome have been reported with the use of
tenofovir prodrugs. In clinical trials of VEMLIDY, there have been no
cases of Fanconi syndrome or proximal renal tubulopathy (PRT). Patients
with impaired renal function and/or taking nephrotoxic agents (including
NSAIDs) are at increased risk of renal-related adverse reactions.
Discontinue VEMLIDY in patients who develop clinically significant
decreases in renal function or evidence of Fanconi syndrome. Monitor
renal function in all patients – See Dosage and Administration.

Lactic Acidosis and Severe Hepatomegaly with Steatosis: Fatal
cases have been reported with the use of nucleoside analogs, including
tenofovir disoproxil fumarate. Discontinue VEMLIDY if clinical or
laboratory findings suggestive of lactic acidosis or pronounced
hepatotoxicity develop, including hepatomegaly and steatosis in the
absence of marked transaminase elevations.

Coadministration of VEMLIDY with drugs that reduce renal function or
compete for active tubular secretion may increase concentrations of
tenofovir and the risk of adverse reactions.

Coadministration of VEMLIDY is not recommended with the following:
oxcarbazepine, phenobarbital, phenytoin, rifabutin, rifampin,
rifapentine, or St. John’s wort. Such coadministration is expected to
decrease the concentration of tenofovir alafenamide, reducing the
therapeutic effect of VEMLIDY. Drugs that strongly affect P-glycoprotein
(P-gp) and breast cancer resistance protein (BCRP) activity may lead to
changes in VEMLIDY absorption.

Consult the full prescribing information for VEMLIDY for more
information on potentially significant drug interactions, including
clinical comments.

Dosage and Administration

Dosage: Adults; 1 tablet taken once daily with food.

Renal Impairment, Screening, and Monitoring: VEMLIDY is not
recommended in patients with CrCl <15 mL/min. In all patients, assess
serum creatinine, estimated creatinine clearance, urine glucose, and
urine protein prior to initiating and during treatment, on a clinically
appropriate schedule. In patients with chronic kidney disease, also
assess serum phosphorus.

VEMLIDY is indicated for the treatment of chronic hepatitis B virus
infection in adults with compensated liver disease.

About Gilead Sciences

Gilead Sciences is a biopharmaceutical company that discovers, develops
and commercializes innovative therapeutics in areas of unmet medical
need. The company’s mission is to advance the care of patients suffering
from life-threatening diseases. Gilead has operations in more than 35
countries worldwide, with headquarters in Foster City, California

Forward-Looking Statement

This press release includes forward-looking statements within the
meaning of the Private Securities Litigation Reform Act of 1995 that are
subject to risks, uncertainties and other factors, including the
possibility of unfavorable results from ongoing and additional clinical
trials involving GS-9674, selonsertib and GS-9688. Further, it is
possible that the parties may make a strategic decision to discontinue
development of GS-9674, selonsertib and GS-9688, and as a result, these
compounds may never be successfully commercialized. These risks,
uncertainties and other factors could cause actual results to differ
materially from those referred to in the forward-looking statements. The
reader is cautioned not to rely on these forward-looking statements.
These and other risks are described in detail in Gilead’s Quarterly
Report on Form 10-Q for the quarter ended June 30, 2018, as filed with
the U.S. Securities and Exchange Commission. All forward-looking
statements are based on information currently available to Gilead, and
Gilead assumes no obligation to update any such forward-looking
statements.

U.S. Full Prescribing Information for Epclusa, Harvoni and Vemlidy
including BOXED WARNINGS, are available atwww.gilead.com.

Epclusa, Harvoni and Vemlidy are registered trademarks of Gilead
Sciences, Inc., or its related companies.

For more information on Gilead Sciences, please visit the company’s
website at www.gilead.com,
follow Gilead on Twitter (@GileadSciences) or call Gilead Public Affairs
at 1-800-GILEAD-5 or 1-650-574-3000